Effect of target pharmaceuticals in the nitrogen and phosphorus removal processes via the nitrite pathway

The inhibitory effects of antibiotics (tetracycline, doxycycline, amoxicillin), an anti-inflammatory (ibuprofen) and an analgesic (paracetamol) on the via nitrite nitrogen and phosphorus removal processes were investigated. Biomass was collected from a sequencing batch reactor (SBR) and was spiked with fixed pharmaceutical concentrations (i.e. 50-500 mgL). Then, batch activity tests were conducted to determine the specific ammonium uptake rate (sAUR), the specific nitrogen uptake rate (sNUR), the specific phosphorus uptake rate (sPUR) under anoxic and aerobic conditions and the specific phosphorus release rate (sPRR). Fluorescence in situ hybridization (FISH) analysis was used to determine the dominant microbial populations. From the single pharmaceuticals, ibuprofen was found to have the highest inhibition for nitritation/denitritation, while doxycycline for the phosphorus uptake and release processes. Denitritation and phosphorus uptake in aerobic conditions were the biological processes that were more severely inhibited by the tested pharmaceuticals, while the phosphorus release process was usually the least sensitive one.